When Ethan Allen Dewey was born on 9 February 1845, in West Springfield, Hampden, Massachusetts, United States, his father, Addison Andrew Dewey, was 34 and his mother, Betsey Catherine Moore, was 28. He married Ellen Augusta Bisbee on 9 February 1870, in West Springfield, Hampden, Massachusetts, United States. They were the parents of at least 1 daughter. He lived in Massachusetts, United States in 1870 and Granville, Hampden, Massachusetts, United States for about 7 years. He died on 21 March 1887, in Westfield, Hampden, Massachusetts, United States, at the age of 42, and was buried in Paucatuck Cemetery, West Springfield, Hampden, Massachusetts, United States.